Is there a way to tell Kubernetes to never run two pods on the same node, an example I have two pods replicas, I want them to be always distributed over zone1/zone2 and never in the same zone together.
apiVersion: app/v1
kind: Deployment
metadata:
name: testApp
labels:
app: testApp-front
namespace:
spec:
replicas: 2
selector:
matchLabels:
app: testApp-front
template:
metadata:
labels:
app: testApp-front
spec:
nodeSelector:
failure-domain.beta.kubernetes.io/zone: zone1The k8s scheduler is a smart piece of software.
The kubernetes scheduler will first determine all possible nodes where a pod can be deployed based on your affinity/anti-affinity/resource limits/etc.
Afterward, the scheduler will find the best node where the pod can be deployed. The scheduler will automatically schedule the pods to be on separate availability zones and on separate nodes if this is possible of course.
P.S. If you never want 2 replicas of a pod to be on the same node, define an anti-affinity rule.
very simple you can use deamon set to run every pod in diffrent node or as the others said you can use pod anti-affinity
Seems like it can be done with Interpod Affinity you can see :
apiVersion: apps/v1
kind: Deployment
metadata:
name: web-server
spec:
selector:
matchLabels:
app: testApp-front
replicas: 3
template:
metadata:
labels:
app: testApp-front
spec:
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: app
operator: In
values:
- testApp-front
topologyKey: "kubernetes.io/hostname"
podAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: app
operator: In
values:
- store
topologyKey: "kubernetes.io/hostname"
containers:
- name: web-testApp-front
image: nginx:1.12-alpineyou can see the full example here
I think you need the concept of pod anti-affinity. This is within one cluster to take care that pods do not reside on one worker-node. https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity